html, body {
  height: 100%;
}

.container {
  height: 100%;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

#btn {
  cursor: pointer;
  width: 300px;
  font-size: 1.2em;
  line-height: 50px;
  -webkit-appearance: none;
  appearance: none;
  color: white;
  background: #ff0081;
  border: none;
}